1. Field of the Invention
The present invention generally relates to an image forming apparatus that employs multilevel random dither processing.
2. Description of the Related Art
When gradation processing based on a random dither method is performed to image data in general, texture that is not present on a document image (data) occurs, which leads to an undesirable image.
One approach is to add a threshold value having a non-periodic component to prevent occurrence of such texture. Such a technique is disclosed, for example, in Japanese Patent Application Laid-open No. H9-93446.
When such a threshold value is added, however, graininess or a feeling of graininess and a feeling of being uneven may disadvantageously appear on an image.